Stent heart devices from Abbott Laboratories (ABT) and Medtronic Inc. (MDT) outperformed an older device from Boston Scientific Corp. (BSX) in three-year data from two studies by better helping patients avoid serious events, Abbott and Medtronic said Monday.

They released fresh study details during the Transcatheter Cardiovascular Therapeutics conference in San Francisco. The data came from separate, company-funded studies that Abbott and Medtronic used to win approval for their drug-coated stents in the U.S. last year. The scaffolds for heart arteries use medication to fight renarrowing and make up a roughly $4 billion global market.

Abbott's Xience stent leads the domestic market behind solid study data, and Medtronic has been working to improve modest sales for its Endeavor stent by highlighting the device's long-term safety profile.

Boston Scientific is a major market player through both home-grown stents and a version of the Abbott stent, called Promus, it sells under a profit-sharing deal.

In both studies released Monday, Abbott and Medtronic devices were measured against the Taxus Express stent from Boston Scientific that formerly led in the U.S. but has since been replaced by a newer version called Taxus Liberte. Boston Scientific noted this fact. Abbott and Medtronic, meantime, have argued that their studies remain relevant because of similarities between the newer and older Boston Scientific devices.

Donald S. Baim, chief medical and scientific officer at Boston Scientific, said in a statement the company was "very pleased" with how Taxus Express performed in the Abbott trial's match-up.

Shares of all involved companies were recently higher, with Abbott up 55 cents, or 1.2%, to $46.52. Medtronic traded up 10 cents to $37.56, while Boston Scientific traded 17 cents higher to $11.14.

The Spirit III study for Abbott's Xience stent has previously shown Xience outperforming the Boston Scientific device on certain fronts, including a composite measurement of serious events including death and heart attacks.

In the three-year data from the 1,002-patient study, Abbott's stent had a 9.1% rate of so-called major adverse cardiac events, compared with a 15.7% rate for Taxus Express, Abbott said. In addition to cardiac death and heart attacks, that composite measurement includes retreatment of the same area in the affected artery.

On another combined measure of events called target lesion failure, the rate was 8.3% with Xience and 14.4% with the Boston Scientific stent, Abbott said.

The company also noted that Xience had no additional cases of late-developing, stent-related clots in the study between years two and three.

Diabetic patients, who are a large segment of the stent market and can be tricky to treat, have become a focal point between the stent makers. Both Abbott and Boston Scientific highlighted how their stents performed among diabetics in the Spirit III study.

Boston Scientific's Baim noted that diabetics with Taxus Express had a lower rate of retreatment in the previously treated area than non-diabetics with the device, and that the stents made by Abbott and Boston Scientific performed similarly on this front.

Abbott cited market-share estimates for July from an outside firm that show Xience and Promus holding more than half the U.S. market combined. Taxus Liberte is next at 20%, followed by a Johnson & Johnson (JNJ) stent and Medtronic's Endeavor.

Endeavor's share has been squeezed by the popularity of Xience and Promus, but also the perception created by some earlier study data that Endeavor isn't a strong performer when it comes to avoiding renarrowing that can lead to repeat procedures.

The fresh evidence from Medtronic's 1,548-patient Endeavor IV study doesn't show a difference between Endeavor and Taxus Express at three years on measures of retreatment. But it does show fewer late-developing clots for Endeavor between years one and three, and this fuels a finding of fewer heart attacks with the Medtronic stent at three years, the company said.

Medtronic also noted better performance for Endeavor on a combined measure of heart attacks and death due to heart events.

Avoiding rare but potentially deadly clots that develop after a year became a serious concern in the coated-stent market after evidence arose three years ago about the dangers of such developments. While clotting worries have since eased, the need to keep coated-stent patients on long courses of anti-clotting drugs has kept doctors from using those devices in many cases.

In the Endeavor IV study, Endeavor had more cases of clots through 360 days than Boston Scientific's stent. But there was one case among Endeavor patients between 360 days and 1,080 days, and 11 cases among Taxus Express patients in that span.

-By Jon Kamp, Dow Jones Newswires; 617-654-6728; jon.kamp@dowjones.com